Rhyolitic tephra marker beds in the Tongariro area, North Island, New Zealand

Abstract

In the Tongariro area 13 rhyolitic tephras erupted from Okataina, Maroa, and Taupo Volcanic Centres over the last 20 000 years are interbedded with local andesitic tephras. The order of succession of the 13 tephras is established by stratigraphy, and is confirmed by their mineralogical composition and by chemical analysis of their titanomagnetites. Seven of the rhyolitic tephras have been previously dated by ¹⁴C, four are dated here, and two are not yet dated. The four new ¹⁴C dates provide ages of c. 12 500 years B.P. for Rotorua Ash (NZ 1186, NZ 1187) ; 9785 ± 170 years B.P. for Papanetu Tephra and Karapiti Lapilli (NZ 1372, NZ 1374); and c 9740 years B.P. for Poronui Tephra.